In all this we assume that the hemispheres do not _natively_ couple any particular sense-impression with any special motor discharge. They only register, and preserve traces of, such couplings as are already organized in the reflex centres below. But this brings it inevitably about that, when a chain of experiences has been already registered and the first link is impressed once again from without, the last link will often be awakened in _idea_ long before it can exist in _fact_. And if this last link were previously coupled with a motion, that motion may now come from the mere ideal suggestion without waiting for the actual impression to arise. Thus an animal with hemispheres acts in _anticipation_ of future things; or, to use our previous formula, he acts from considerations of distant good and ill. If we give the name of _partners_ to the original couplings of impressions with motions in a reflex way, then we may say that the function of the hemispheres is simply to bring about _exchanges among the partners_. Movement _m^n_, which natively is sensation _s^n_'s partner, becomes through the hemispheres the partner of sensation _s^1, s^2_, or _s^3_. It is like the great commutating switch-board at a central telephone station. No new elementary process is involved; no impression nor any motion peculiar to the hemispheres; but any number of combinations impossible to the lower machinery taken alone, and an endless consequent increase in the possibilities of behavior on the creature's part. All this, as a mere scheme,[7] is so clear and so concordant with the general look of the facts as almost to impose itself on our belief; but it is anything but clear in detail. The brain-physiology of late years has with great effort sought to work out the paths by which these couplings of sensations with movements take place, both in the hemispheres and in the centres below. So we must next test our scheme by the facts discovered m this direction. We shall conclude, I think, after taking them all into account, that the scheme probably makes the lower centres too machine-like and the hemispheres not quite machine-like enough, and must consequently be softened down a little. So much I may say in advance. Meanwhile, before plunging into the details which await us, it will somewhat clear our ideas if we contrast the modern way of looking at the matter with the _phrenological_ conception which but lately preceded it. THE PHRENOLOGICAL CONCEPTION.